Museum of Science and Industry

While human eyes can see many colors, the greeneye fish—found at ocean depths between 160 to 3,300 feet—can really only detect a green color, meaning any non-green predators should have an advantage over this tiny fish. Yet scientists at Duke University discovered that these greeneye fish have color-changing lenses in their eyes, which pick up ultraviolet light and transmit it as a green color back to the retina and on to their brain. Many fish that deep in the ocean are a blue-violet color, so the greeneye fish lenses adapt to see their predators' likely color, though it's still unclear how they work.

This is different than mammals on land, who use a reflective surface called the tapetum in the back of their eye to see better in the dark. You can learn about these in the daily Dissect an Eye At MSI program, where we get a look at cow tapetums all the time!

Fish Eyes Go Green [Science News for Kids]

Image: Edie Widder/NOAA Ocean Explorer